In the field of glass sheets, glass sheets have been increased in size for improvement in efficiency of production of liquid crystal displays and increase in size of liquid crystal displays. A glass sheet increased in size can yield more glass substrates and thus improve production efficiency as well as allow production of glass substrates compatible with large-sized liquid crystal displays.
If a glass sheet has a flaw in a selvage part thereof, the flaw may develop into a crack or the like in the glass sheet. Selvage parts of a glass sheet are therefore chamfered. Furthermore, in order to increase throughput per unit time and lower the production cost, the speed of conveying (speed of processing) a glass sheet is increased.
By observing an edge surface of a glass sheet subjected to the chamfering through a microscope, fine projections and recesses can be found on the edge surface of the glass sheet. Such a glass sheet may have a chip or a crack in a following process (process by a customer), and therefore the edge surface of the glass sheet is polished into an even surface. However, in order to polish the edge surface of the glass sheet into an even surface, an area of the glass sheet reserved for the polishing needs to be set larger. Accordingly, the polishing time is increased, and it is difficult to further increase the glass sheet conveyance speed (processing speed). Besides, when an edge surface of an enlarged and thinned glass sheet is polished, a counter force to the processing force from a grinding or polishing tool to the glass sheet (grinding resistance or polishing resistance) strongly acts, causing a chip or a crack in the edge surface of the glass sheet.
Various methods for processing an edge surface of a glass sheet having microscopic projections and recesses on the edge surface of the glass sheet have been invented (Patent Literatures 1 to 3).